This is described for example in DD 125 035, where deactivation and/or destruction of the titanium halide catalyst is achieved by adding a stoichiometric amount of water or by washing the phosphorus-containing alkoxylation products with water or alkalis.
Aftertreatments of this kind for destroying and/or deactivating the catalyst, however, have disadvantages. They necessitate reactors additionally; there is a deterioration in the space-time yield; and losses of product occur. The washing waters produced must be disposed of, which is costly and inconvenient. And, not least, the catalyst employed is lost to further use. Apart from the processes with homogeneous catalysis, the use of heterogeneous catalysts is largely unknown.
One heterogeneous catalysis system was recently described by Yang, Jin-Fei in Yingyong Huaxue 2003, 20 (2), 201-202, using TiSiW12O40/TiO2, for the preparation of (ClCH2CH2O)3PO. A disadvantage associated with the use of the catalyst is the comparatively costly and inconvenient preparation.
A continuous production method of 2-haloalkylated phosphates by means of heterogeneous catalysts is described in CN 1 034 206. In that case BeO is employed. The process permits the preparation of low-acid products (acid number<0.2 mg KOH/g solid) such as (MeCHClCH2O)3PO, (ClCH2CHClCH2O)3PO, and (ClCH2CH2O)3PO. A disadvantage associated with the use of the catalyst is the potential release of highly toxic beryllium salts.
U.S. Pat. No. 3,557,260 proposes the use of sulfates of various elements. The required reaction time is approximately 80 hours and is much longer, for economic operations, than the state of the art.
The object of the present invention was therefore to develop a process for preparing phosphorus-containing alkoxylation products, using heterogeneous catalysts, while avoiding the disadvantages of the prior art.